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arXiv · 1604.07320

Ballistic graphene Josephson junctions from the short to the long regime

I. V. Borzenets·F. Amet·C. T. Ke·A. W. Draelos·M. T. Wei·A. Seredinski·K. Watanabe·T. Taniguchi·Y. Bomze·M. Yamamoto·S. Tarucha·G Finkelstein
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Abstract

We investigate the critical current, $I_C$, of ballistic Josephson junctions made of encapsulated graphene/boron-nitride heterostructures. We observe a crossover from the short to the long junction regimes as the length of the device increases. In long ballistic junctions, $I_S$ is found to scale as $\propto \exp(-k_bT/δE)$. The extracted energies $δE$ are independent of the carrier density and proportional to the level spacing of the ballistic cavity, as determined from Fabry-Perot oscillations of the junction normal resistance. As $T\rightarrow 0$ the critical current of a long (or short) junction saturates at a level determined by the product of $δE$ (or $Δ$) and the number of the junction's transversal modes.

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I. V. Borzenets, F. Amet, C. T. Ke, A. W. Draelos, M. T. Wei, A. Seredinski, K. Watanabe, T. Taniguchi, Y. Bomze, M. Yamamoto, S. Tarucha, G Finkelstein. 2016-10-11. Ballistic graphene Josephson junctions from the short to the long regime. https://doi.org/10.1103/physrevlett.117.237002

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